Rotating Coalescing Element with Directed Liquid Drainage and Gas Outlet

ABSTRACT

A rotating coalescer having an ejected coalesced liquid separating device is described. The separating device prevents re-entrainment of liquid into a stream of filtered gas. The rotating coalescer includes a rotating filter element or coalescing cone stack positioned within a rotating coalescer housing. The outer surface of the rotating filter element or the outlet of the coalescing cone stack is displaced from the inner surface of the rotating coalescer housing. The gap between the rotating filter element or the coalescing cone stack and the rotating coalescer housing allows for ejected coalesced liquid, such as oil, to accumulate on the inner surface of the rotating coalescer housing for drainage and allows for filtered gas, such as air, to exit through a clean gas outlet of the rotating coalescer housing.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Patent ApplicationNo. 62/211,538, entitled “ROTATING COALESCING ELEMENT WITH DIRECTEDLIQUID DRAINAGE AND GAS OUTLET,” by Schwandt et al., filed on Aug. 28,2015 and the contents of which are herein incorporated by reference inthe entirety and for all purposes.

TECHNICAL FIELD

The present application relates to rotating coalescing elements.

BACKGROUND

During operation of an internal combustion engine, a fraction ofcombustion gases can flow out of the combustion cylinder and into thecrankcase of the engine. These gases are often called “blowby” gases.The blowby gases include a mixture of aerosols, oils, and air. If venteddirectly to the ambient, the blowby gases can harm the environment.Accordingly, the blowby gases are typically routed out of the crankcasevia a crankcase ventilation system. The crankcase ventilation system maypass the blowby gases through a coalescer (i.e., a coalescing filterelement) to remove a majority of the aerosols and oils contained in theblowby gases. The coalescer includes filter media. The filtered blowbygases (“clean” gases) are then either vented to the ambient (in opencrankcase ventilation systems) or routed back to the air intake for theinternal combustion engine for further combustion (in closed crankcaseventilation systems).

Some crankcase ventilation systems utilize rotating coalescers thatincrease the filter efficiency of the coalescing filter elements byrotating the filter media during filtering. In rotating filtercartridges, the contaminants (e.g., oil droplets suspended andtransported by blowby gases) are separated inside the filter media ofthe filter cartridge through the particle capture mechanisms of inertialimpaction, interception, diffusion, and gravitational forces onto thefibers. By rotating the filter media, inertial impaction andgravitational forces are enhanced by the additional centrifugal force.Additionally, the rotation of the filter cartridge can create a pumpingeffect, which reduces the pressure drop through the filtration system.Rotating filter cartridges may include fibrous filters as well ascentrifugal separation devices.

The centrifugal forces caused by the rotation tend to eject coalescedliquid droplets along the entire axial height of the filter media.Depending on the location of ejection and the speed of rotation, theseparated liquid droplets may be re-entrained into the flow stream offiltered air. Further, the ejected liquid droplets may be collected on astationary surface of the coalescer housing at an undesirable area. Thisincreased liquid carry-over of the rotating coalescer can reduce theefficiency of the filtration system. Further, the increased liquidcarry-over can make it difficult to position a gas flow outlet for thecoalescer housing directly opposite of the rotating coalescer outerdiameter due to direct ejection of the coalesced droplets towards theoutlet.

SUMMARY

One example embodiment relates to a filtration system. The filtrationsystem includes a filtration system housing having an inlet and anoutlet. A rotating coalescer element is positioned within the filtrationsystem housing and in fluid communication with the inlet and the outlet.The rotating coalescer element is configured to separate a suspendedliquid from a fluid received through the inlet. The rotating coalescerelement includes a first endplate, a second endplate, and a coalescingdevice positioned between the first endplate and the second endplate.The rotating coalescer element further includes a rotating coalescerhousing extending between and coupled to the first endplate and thesecond endplate. The rotating coalescer housing is radially displacedfrom an outer surface of the coalescing device such that a gap existsbetween an inner wall of the rotating coalescer housing and the outersurface of the coalescing device. The rotating coalescer housingincludes a clean gas outlet adjacent the first endplate and a liquidoutlet adjacent the second endplate. The rotating coalescer housingincluding a circumferential ring positioned near the gas outlet thatprevents separated liquid accumulated on the inner wall from passingthrough the clean gas outlet.

Another example embodiment relates to a rotating coalescer element. Therotating coalescer element is configured to separate a suspended liquidfrom a fluid. The rotating coalescer element includes a first endplate,a second endplate, and a coalescing device positioned between the firstendplate and the second endplate. The rotating coalescer element furtherincludes a rotating coalescer housing extending between and coupled tothe first endplate and the second endplate. The rotating coalescerhousing is radially displaced from an outer surface of the coalescingdevice such that a gap exists between an inner wall of the rotatingcoalescer housing and the outer surface of the coalescing device. Therotating coalescer housing includes a clean gas outlet adjacent thefirst endplate and a liquid outlet adjacent the second endplate. Therotating coalescer housing including a circumferential ring positionednear the gas outlet that prevents separated liquid accumulated on theinner wall from passing through the clean gas outlet.

These and other features, together with the organization and manner ofoperation thereof, will become apparent from the following detaileddescription when taken in conjunction with the accompanying drawings,wherein like elements have like numerals throughout the several drawingsdescribed below.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 shows a cross-sectional view of a filtration system is shownaccording to an example embodiment.

FIG. 2 shows a cross-sectional view of the rotating filter element ofthe filtration system of FIG. 1.

FIG. 3 shows a perspective view of the rotating filter element of thefiltration system of FIG. 1.

FIG. 4 shows another perspective view of the rotating filter element ofthe filtration system of FIG. 1.

FIG. 5 shows another cross-sectional view of the rotating filter elementof the filtration system of FIG. 1.

FIG. 6 is a cross-sectional view of a rotating coalescer elementaccording to an example embodiment.

FIG. 7 is a cross-sectional view of a rotating filter element accordingto another example embodiment.

DETAILED DESCRIPTION

Referring to the figures generally, a rotating coalescer having anejected coalesced liquid separating device is described. The separatingdevice prevents re-entrainment of liquid into a stream of filtered gas.The rotating coalescer includes a rotating filter element or coalescingcone stack positioned within a rotating coalescer housing. The outersurface (i.e., the clean side) of the rotating filter element or theoutlet of the coalescing cone stack is displaced from the inner surfaceof the rotating coalescer housing. The gap between the rotating filterelement or the coalescing cone stack and the rotating coalescer housingallows for ejected coalesced liquid, such as oil, to accumulate on theinner surface of the rotating coalescer housing for drainage and allowsfor filtered gas, such as air, to exit through a clean gas outlet of therotating coalescer housing. In some arrangements, the rotating coalescerhousing includes a rib that prevents accumulated liquid from flowingthrough the clean gas outlet. In further arrangements, the inner surfaceof the rotating coalescer housing is angled to assist with drainage ofthe accumulated liquid.

Referring to FIG. 1, a cross-sectional view of a filtration system 100is shown according to an example embodiment. The filtration system 100includes a filtration system housing 102 having an inlet 104 and anoutlet 106. The filtration system housing 102 is a stationary housing.The inlet 104 receives fluid to be filtered, such as crankcase blowbygases, and the outlet 106 outputs filtered fluid to a system, such as aninternal combustion engine (e.g., a diesel internal combustion engine).The filtration system 100 includes a rotating filter element 108. Therotating filter element 108 is a rotating coalescer element. Therotating filter element 108 includes filter media 110. The filter media110 shown in FIG. 1 is arranged in a cylindrical shape. The filter media110 is a coalescing fibrous filter media. The rotating filter element108 includes a first endplate 112 and a second endplate 114. The filtermedia 110 is positioned between the first endplate 112 and the secondendplate 114. In some arrangements, the filter media 110 is sealed tothe first endplate 112 and the second endplate 114. The rotating filterelement 108 further includes a rotating coalescer housing 116. Therotating coalescer housing 116 extends between and is coupled to thefirst endplate 112 and the second endplate 114. The rotating coalescerhousing 116 is radially displaced from an outer surface of the filtermedia 110. Generally, the rotating filter element 108 separates asuspended liquid in the fluid. In arrangements where the filtrationsystem 100 is a crankcase ventilation system, the rotating filterelement 108 separates oils and aerosols suspended in the crankcaseblowby gases. The rotating filter element 108 is described in furtherdetail below with respect to FIGS. 2 through 7.

Referring to FIGS. 2 through 5, various views of the rotating filterelement 108 are shown. As shown best in FIGS. 2 and 5, the rotatingfilter element 108 includes a central axis 118. During operation, therotating filter element 108 rotates about a central axis. Fluid to befiltered enters the filtration system housing 102 through the inlet 104.The fluid flows through the filter media 110 as shown by flow arrows 120in FIG. 5. As the fluid passes through the filter media 110, liquiddroplets dispersed in the fluid are coalesced and separated from thefluid by the filter media 110. Due to the rotation of the rotatingfilter element 108 and the centrifugal force imparted on the separatedliquid, the separated liquid may be ejected from the outlet face of thefilter media 110. As noted above, the inner wall of the rotatingcoalescer housing 116 is separated from the outlet face of the filtermedia 110 (e.g., by a distance D). The separation distance D permits theejected liquid to accumulate along the inner wall of the rotatingcoalescer housing 116 while still providing space for the filtered fluidto flow out of the rotating filter element 108. As the separated liquidaccumulates on the inner wall of the rotating coalescer housing 16, theseparated liquid may form a film of liquid along the inner wall of therotating coalescer housing 116. The separated liquid flows to a drain(as designated by the drainage arrow 122). The filtered fluid exits therotating filter element 108 through a plurality of gas outlets 124formed between the first endplate 112 and the rotating coalescer housing116. The accumulated liquid along the inner wall of the rotatingcoalescer housing 116 exits the rotating filter element 108 through aplurality of liquid outlets 126 formed in the rotating coalescer housing116 and a plurality of drains 128 formed in the second endplate 114. Asshown best in FIG. 3, the liquid outlets 126 are formed near theopposite end of the rotating coalescer housing 116 from the gas outlets124. As described in further detail below, the rotating coalescerhousing 116 includes features that assist in preventing the accumulatedfluid from flowing out of the gas outlets 124. In some arrangements, therotating coalescer housing 116 and the first endplate 112, or at least aportion there of, are formed as a single piece of injection moldedthermoplastic.

In some arrangements, the inner wall of the rotating coalescer housing116 includes a circumferential ring 130 positioned near the gas outlets124 of the rotating filter element 108. The circumferential ring 130prevents the separated liquid from flowing through the gas outlets 124.Due to the rotation of the rotating filter element 108, the film ofaccumulated liquid that forms along the inner wall of the rotatingcoalescer housing 116 can only reach a certain thickness. The height ofthe circumferential ring 130 with respect to the inner wall of therotating coalescer housing 116 is greater than the maximum thickness ofthe film of accumulated liquid thereby preventing the liquid fromexiting the rotating filter element through the gas outlets 124.

In further arrangements, the rotating coalescer housing 116 may beangled at a draft angle a away from the gas outlets 124. In sucharrangements, the rotating coalescer housing is narrower at the endadjacent to the gas outlets 124 (i.e., the first endplate 112) and widerat the end adjacent to the liquid outlets 126 (i.e., the second endplate114). Thus, the rotating coalescer housing 116 may be slightly conical,convex, or concave in shape. During rotation, the centrifugal forces onthe accumulated liquid will move the accumulated along angled wall ofthe rotating coalescer housing 116 in an axial direction towards theliquid outlets 126 and away from the gas outlets 124. In somearrangements, the centrifugal forces on the accumulated liquid in theaxial direction are greater than gravity. In such arrangements, the gasoutlet 124 and the liquid outlet can be flipped in the direction ofgravity (e.g., as shown in FIG. 7).

Neglecting viscous and/or shear forces from the flow of gas between thefilter media 110 and the rotating coalescer housing 116, the accumulatedliquid on the inner wall of the rotating coalescer housing 116 forms a“near vertical” liquid film, where the equilibrium surface angle withrespect to axis =a (if no drainage occurred and the accumulated liquidwere trapped within the rotating filter element 108) would beapproximately tan⁻¹(1/Gradial), where the Gradial is defined by equation(1) below.

ω² *R=Gradial≥˜1000   (1)

In equation 1, ω is the rotational speed of the rotating filter element108 during operation and R is the distance between the central axis 118and the inside of the rotating coalescer housing 116. Accordingly, theheight of the circumferential ring 130, the draft angle α, or acombination thereof creates an effective angle greater thantan⁻¹(1/Gradial) to achieve drainage in the desired direction (i.e.,away from the gas outlets 124 and towards the liquid outlets 126. Forexample, for a Gradial of approximately 1000, the draft angle 132 isapproximately 0.06 degrees.

Still referring to FIGS. 1 through 5, in some arrangements, the rotatingcoalescer housing 116 includes a plurality of support ribs 132projecting from the inner surface of the rotating coalescer housing 116to the outlet face of the filter media 110. The support ribs 132 providesupport to the flexible fibrous media 110 during rotation of the filterelement 108 to prevent excessive deformation of the filter media 110during high speed rotation. In order to allow filtered fluid to exitthrough the gas outlets 124, the support ribs 132 may include a numberof first through-holes that allow the filtered fluid to pass between thesupport ribs 132. Alternatively, gas outlets 124 may be positionedbetween adjacent sets of support ribs 132 and between the outermostsupport ribs 132 and the first and second endplates 112 and 114.Additionally, to allow the accumulated liquid to drain, the support ribs132 include a number of second through-holes that allow the accumulatedliquid to pass between the support ribs 132. Alternatively, liquidoutlets 126 may be positioned between adjacent sets of support ribs 132and between the outermost support ribs 132 and the first and secondendplates 112 and 114.

In some arrangements, an axial rib ring extends 134 from the gas outletend of the rotating coalescer housing 116 adjacent to the filter media110. The axial rib ring 134 extends into the rotating coalescer housing116 beyond the axial location of the circumferential ring 130, whichprevents accumulated liquid from migrating to the gas outlets 124. Theaxial rib ring 134 acts as a weir that prevents accumulated liquidexiting the filter media 110 from ejecting directly to the gas outlets124.

Referring to FIG. 6, a cross-sectional view of a rotating coalescerelement 600 is shown according to an example embodiment. The rotatingcoalescer element 600 is similar to the rotating filter element 108 offiltration system 100. Accordingly, like numbering is used between therotating coalescer element 600 of FIG. 6 and the rotating filter elementof FIGS. 1 through 5. The only difference between the rotating coalescerelement 600 and the rotating filter element 108 is that the rotatingcoalescer element 600 does not utilize filter media to separate a liquidsuspended in the fluid flowing through the rotating coalescer element600. Rather, the rotating coalescer element 600 utilizes a centrifugecone stack 602. The centrifuge cone stack 602 includes a plurality ofaxially spaced centrifuge cones 604. Each of the cones is angled withrespect to the radial direction. As the gas passes through the spacebetween each of the axially spaced centrifuge cones 604, the angle ofthe individual axially spaced centrifuge cones 604 causes an abruptchange in direction of the gas. The abrupt change of direction separatesthe suspended liquid due to the higher inertia of the liquid as comparedto the gas.

FIG. 7 shows a cross-sectional view of a rotating filter element 700according to an example embodiment. The rotating filter element 700 issimilar to the rotating filter element 108 of filtration system 100.Accordingly, like numbering is used between the rotating filter element700 of FIG. 7 and the rotating filter element of FIGS. 1 through 5. Asshown in FIG. 7, the rotating filter element 700 is oriented in theopposite direction with respect to gravity 702 than the rotating filterelement 108. Accordingly, the accumulated liquid is drained from therotating filter element 700 against the force of gravity. The drainageis achieved because the centrifugal force on the accumulated liquid ishigh enough to overcome the force of gravity. The orientation of thefilter element 700 permits a top inlet of the gas-liquid mixture intothe device and a bottom clean gas outlet. Such an arrangement may bepreferred for certain crankcase ventilation applications in which thesource of the aerosol laden blowby gas to be cleaned is above thelocation of the rotating coalescing device.

The above-described rotating coalescer and filter elements may be usedin crankcase ventilation systems. In some arrangements, theabove-described rotating coalescer and filter elements are used inhigh-speed rotating coalescer arrangements in which the radial g-forceat the inner diameter of the rotating coalescer housing 116 is at least1000 times the force of gravity.

The above-described rotating coalescer and filter elements provide anumber advantages in accordance with various embodiments. By changingthe shape of the rotating coalescer housing (e.g., the rotatingcoalescer housing 116), separated liquid can be directed to a desiredlocation by harnessing axial and radial components of the centrifugalforce created by the rotation. This allows for an unlimited amount oflocations for accumulated liquid to be ejected from the rotatingcoalescer housing. This minimizes or eliminates the risk of accumulatedliquid becoming re-entrained into the filtered fluid via the gas outlet.Similarly, by utilizing the centrifugal forces to move the accumulatedliquid, the coalescing element could be operated at any angle, providedthat the outlet liquid ejected from the rotating body is captured in anarea of the stationary housing which directs the ejected liquid away anddoes not allow it to recombine with the clean gas outlet.

It should be noted that any use of the term “example” herein to describevarious embodiments is intended to indicate that such embodiments arepossible examples, representations, and/or illustrations of possibleembodiments (and such term is not intended to connote that suchembodiments are necessarily extraordinary or superlative examples).

As used herein, the term “about” or “approximately” when coupled to anumber or a range means plus or minus five percent of the modifiednumber or range. When a range is described as being between two numbers,the range is intended to be inclusive of the two numbers that define therange.

The terms “coupled” and the like as used herein mean the joining of twomembers directly or indirectly to one another. Such joining may bestationary (e.g., permanent) or moveable (e.g., removable orreleasable). Such joining may be achieved with the two members or thetwo members and any additional intermediate members being integrallyformed as a single unitary body with one another or with the two membersor the two members and any additional intermediate members beingattached to one another.

References herein to the positions of elements (e.g., “top,” “bottom,”“above,” “below,” etc.) are merely used to describe the orientation ofvarious elements in the FIGURES. It should be noted that the orientationof various elements may differ according to other example embodiments,and that such variations are intended to be encompassed by the presentdisclosure.

It is important to note that the construction and arrangement of thevarious example embodiments are illustrative only. Although only a fewembodiments have been described in detail in this disclosure, thoseskilled in the art who review this disclosure will readily appreciatethat many modifications are possible (e.g., variations in sizes,dimensions, structures, shapes and proportions of the various elements,values of parameters, mounting arrangements, use of materials, colors,orientations, etc.) without materially departing from the novelteachings and advantages of the subject matter described herein. Forexample, elements shown as integrally formed may be constructed ofmultiple parts or elements, the position of elements may be reversed orotherwise varied, and the nature or number of discrete elements orpositions may be altered or varied. The order or sequence of any processor method steps may be varied or re-sequenced according to alternativeembodiments. Additionally, features from particular embodiments may becombined with features from other embodiments as would be understood byone of ordinary skill in the art. Other substitutions, modifications,changes and omissions may also be made in the design, operatingconditions and arrangement of the various example embodiments withoutdeparting from the scope of the present invention.

What is claimed is:
 1. A filtration system comprising: a filtrationsystem housing having an inlet and an outlet, a rotating coalescerelement positioned within the filtration system housing and in fluidcommunication with the inlet and the outlet, the rotating coalescerelement configured to separate a suspended liquid from a fluid receivedthrough the inlet, the rotating coalescer element including: a firstendplate, second endplate, a coalescing device positioned between thefirst endplate and the second endplate, and a rotating coalescer housingextending between and coupled to the first endplate and the secondendplate, the rotating coalescer housing radially displaced from anouter surface of the coalescing device such that a gap exists between aninner wall of the rotating coalescer housing and the outer surface ofthe coalescing device, the rotating coalescer housing including a cleangas outlet adjacent the first endplate and a liquid outlet adjacent thesecond endplate, the rotating coalescer housing including acircumferential ring positioned near the gas outlet that preventsseparated liquid accumulated on the inner wall from passing through theclean gas outlet.
 2. The filtration system of claim 1, wherein thecoalescing device includes a fibrous filter media.
 3. The filtrationsystem of claim 1, wherein the coalescing device includes a coalescercone stack.
 4. The filtration system of claim 1, wherein the rotatingcoalescer housing is narrower at a first end adjacent to the gas outletand wider at a second end adjacent to the liquid outlet.
 5. Thefiltration system of claim 4, wherein the accumulated liquid is drainedfrom the rotating coalescer element against the force of gravity.
 6. Thefiltration system of claim 1, wherein the rotating coalescer element isa high-speed rotating coalescer element that creates a radial g-force atthe inner wall of the rotating coalescer housing of at least 1000 timesthe force of gravity.
 7. The filtration system of claim 1, wherein thefluid is crankcase blowby gas received from an internal combustionengine.
 8. The filtration system of claim 1, wherein the second endplatecomprises a plurality of drains.
 9. The filtration system of claim 1,wherein the rotating coalescer housing comprises a support ribprojecting from the inner wall to provide support to the coalescingdevice.
 10. The filtration system of claim 9, wherein the support ribcomprises a through-hole configured to allow filtered fluid to passthrough the support rib.
 11. A rotating coalescer element configured toseparate a suspended liquid from a fluid, the rotating coalescer elementcomprising: a first endplate, a second endplate, a coalescing devicepositioned between the first endplate and the second endplate, and arotating coalescer housing extending between and coupled to the firstendplate and the second endplate, the rotating coalescer housingradially displaced from an outer surface of the coalescing device suchthat a gap exists between an inner wall of the rotating coalescerhousing and the outer surface of the coalescing device, the rotatingcoalescer housing including a clean gas outlet adjacent the firstendplate and a liquid outlet adjacent the second endplate, the rotatingcoalescer housing including a circumferential ring positioned near thegas outlet that prevents separated liquid accumulated on the inner wallfrom passing through the clean gas outlet.
 12. The rotating coalescerelement of claim 11, wherein the coalescing device includes a fibrousfilter media.
 13. The rotating coalescer element of claim 11, whereinthe coalescing device includes a coalescer cone stack.
 14. The rotatingcoalescer element of claim 11, wherein the rotating coalescer housing isnarrower at a first end adjacent to the gas outlet and wider at a secondend adjacent to the liquid outlet.
 15. The rotating coalescer element ofclaim 14, wherein the accumulated liquid is drained from the rotatingcoalescer element against the force of gravity.
 16. The rotatingcoalescer element of claim 11, wherein the rotating coalescer element isa high-speed rotating coalescer element that creates a radial g-force atthe inner wall of the rotating coalescer housing of at least 1000 timesthe force of gravity.
 17. The rotating coalescer element of claim 11,wherein the fluid is crankcase blowby gas received from an internalcombustion engine.
 18. The rotating coalescer element of claim 11,wherein the second endplate comprises a plurality of drains.
 19. Therotating coalescer element of claim 11, wherein the rotating coalescerhousing comprises a support rib projecting from the inner wall toprovide support to the coalescing device.
 20. The rotating coalescerelement of claim 19, wherein the support rib comprises a through-holeconfigured to allow filtered fluid to pass through the support rib.